.domino {
  border: 1px solid black;
  width: 40px;
  height: 80px;
  display: flex;
  flex-direction: column;
  margin: 5px;
  background-color: white;
}

.domino-half {
  flex: 1;
  display: flex;
  justify-content: center;
  align-items: center;
  font-size: 18px;
  font-weight: bold;
}

.domino-half.top {
  border-bottom: 1px solid black;
}